Down 2-0 less than 24 hours ago, Brazil has come back to tie the United States in the first round of Davis Cup World Group play, thanks to Thomaz Bellucci's 2-6, 6-4, 6-7 (7), 6-4, 6-3 win over John Isner. With the fifth and deciding rubber between Sam Querrey and Thiago Alves underway, here are some quick thoughts on this just-completed battle of No. 1s:

—Bellucci's match against Querrey on Friday was deemed a must-win for Brazil based on the great likelihood of the Bryan brothers taking the doubles point. That didn't happen, and Bellucci made the most of his mulligan. There were lots of points today at which Bellucci, who didn't put up a great effort in his first singles match, could have caved: After losing a lopsided first set; after losing a tight tiebreaker to trail two sets to one; and after losing a 40-0 lead on serve at 1-1 in the fifth set. But in each instance, the Brazilian fought back, displaying what makes his game so appealing along the way. Belluccis mixed slice and power nicely, and the fact that he's left-handed made rallies even more difficult for Isner. In the end, Bellucci's patience was his most important attribute, as this was just as much a mental victory as a physical triumph.

—Isner has won five-setters in the past despite looking drained. Having the most powerful serve in tennis is a big reason for that. But Isner's fitness seemed to betray him by the latter stages of this match. Down two set points in the fourth, Isner erased both with unreturned serves, but double-faulted on the ensuing deuce point. Clearly, Isner was taking his best shot and seeing if it stuck, a strategy he continued to follow in the fifth set. On Bellucci's third set point, Isner put a short forehand into the net, and Brazil could see the finish line of this fourth rubber.

—Bellucci also won plenty of points on his serve, owing to Isner's average returning on the day (he broke Bellucci just twice) and his ability to move the ball around the box. He needed strong serving at 3-3 in the fifth, when Isner took a 0-30 lead. The subsequent points were crucial for Bellucci; they weren't match points, but they weren't that far off. He won all four with a mixture of timely serves and flat strikes to the corners. When Bellucci found his range with his forehand, Isner was in a perilous position.

—The seventh game of the fifth set, with Isner serving down 3-4, was the one that broke the American, literally and figuratively. Isner briefly appeared to escape it with a short forehand winner, but Bellucci challenged the call and it was reversed. From that point onward, Isner was under relentless pressure. His first serve and forehand failed him in this game; he went for too much without much payoff. Bellucci was hardly aggressive in this game—the majority of his points came from looping forehands that eluded Isner or forced him out of position—but he didn't need to be. On his sixth break point, earned thanks to an all-too-common Isner forehand error, Bellucci played another patient rally, slicing a backhand deep to Isner's backhand corner. The American's slice reply found the net, and Bellucci easily served out the match.

—Can Brazil complete the comeback? Alves gave a nice effort against Isner on Friday, despite losing in straight sets, but Querrey is the fitter and more well-rounded U.S. singles star. Even though the yellow and green have clawed back to even, it would still be a shock to see Alves, who doesn't have the weapons to trouble Querrey, take this must-win match on the road. But saying all that, Querrey is under tremendous pressure to stop the bleeding, and he's had a history of falling short in very important matches. Brazil's supporters, who you can hear easily among the sparse crowd in Jacksonville, would love to see Sam slip up again.